How Cement Mixers Work

Most construction equipment is easy to understand. Cranes move things up and down. Dump trucks load, move out and unload. Bulldozers push and graders grade. The one exception is the unassuming cement mixer, beloved by kids, hated by drivers in a hurry, and misunderstood by most people outside the cab of the 30,000-pound (13,608-kilogram) behemoth.

While concrete has been around in one form or another since before the Romans built the ancient Abbey Road, the transportation mixer is a 20th-century creation. But recent invention or not, mixers are here to stay.

The misunderstanding starts with the name. What people call a cement mixer is known in the construction industry as a concrete mixer, and comes in a variety of types, sizes, and configurations to handle the many tasks that come before it every day. The need to take on so many roles means that the machine is dynamic, changing shape and form as people use concrete to meet their changing needs.

In this article, we'll look at some of the main types of mixers, from the traditional drum-shaped ready-mix transportation mixer to the less common but increasingly popular volumetric mixer, essentially a concrete plant on wheels. Cement mixers and how they work are a fascinating combination of old and new technology. You'll never see a cement mixer the same way again.

But before we get started, let's clarify the difference between cement and concrete. When it comes to baking, the difference between concrete and cement is the difference between flour and a loaf of bread. Concrete is the generic term for a mixture of aggregates - usually stone or gravel, water and cement. Modern cement is a complex mixture of finely ground minerals, known generically as "Portland". Concrete is made by mixing the three ingredients in a mixer, whether the mixer is standing still or traveling down the road, and the water is absorbed by the cement, which then binds the aggregates together to form the concrete.